Pathogenesis 831 



probably that of Krai,* which is as follows: "A good deal of 

 the material from the scutula is rubbed up in a porcelain 

 mortar dish with previously heated diatomaceous earth, with 

 a porcelain pestle, without exerting too much pressure. 

 Melted agar-agar tubes are then inoculated with two or three 

 loopfuls of the crushed material and poured into Petri dishes. 

 Greater dilution can be made if desired. The plates are ex- 

 amined after forty-eight hours. 



Cultures may, however, be directly made with material 

 from the center of a scutulum. Agar-agar should be used, as 

 the cultures grow best at the body temperature. The 

 young colonies that appear in forty -eight hours can easily be 

 transplanted by fishing under a lens. 



The best medium was found by Sabouraud to consist of 

 maltose, 4; peptone, 2; fucus crispi, 1.5; water, 100. 



As the colonies eventually become quite large it is recom- 

 mended that, instead of tubes, they be made in Erlenmeyer 

 flasks, the transplanted little colonies being placed at the 

 center of the medium congealed upon the bottom of the flask. 



The appearance of the cultures varies considerably. 

 Plaut gives two principal varieties : ( i ) The waxy type a yel- 

 lowish mass of a waxy character with radiating folds and a 

 central elevation. As a rule no aerial hypha, but occasionally 

 short aerial hypha. 



(2) The downy type this forms a white disk with a velvety 

 or plush-like covering of white aerial hypha. Sometimes in- 

 stead of white the color is yellowish or reddish. A marked 

 dimple with a smaller elevation usually occurs in the middle, 

 and there may be radial folds. 



Pathogenesis. The micro-organism is pathogenic for 

 mice, rabbits, cats, dogs, hens, and men, in all of whom typical 

 scutula form. Scutulum formation has not been observed in 

 guinea-pigs. The disease readily spreads from animal to 

 animal by direct contact, and by indirect contact by the use 

 of combs, hair-brushes, and similar objects. On account of 

 its chronicity, its obstinacy, its disfigurement, and its trans- 

 missibility it is a dangerous disease, and one that requires 

 prompt isolation of the patient and the utmost care for the 

 prevention of contagion. 



*See Plaut, in Kolle and Wassermann's "Pathogene Mikroorgan- 

 ismen," i, p. 608. 



